1. Field of the Invention
This invention relates to a shielding method of a flat circuit body, such as a FPC(Flexible Printed Circuit) and a FFC (Flexible Flat Cable), to be covered by a shield film as a shielded flat circuit body and a wiring harness having the shielded flat circuit body.
2. Description of the Related Art
Various electronic apparatuses are installed in a car as a vehicle. In the car, a wiring harness 50 (shown in FIG. 10) is wired for transmitting electric power from a power supply, such as a battery, and control signals from a controller to the electronic apparatus. The wiring harness 50 shown in FIG. 10 includes a connector housing (not shown) and a shielded FFC 51. The connector housing receives a later-described terminal 53 of the shielded FFC 51 therein.
The shielded FFC 51 has a flat cable 52 and a terminal 53. The flat cable 52 has a plurality of conductors 54 arranged in parallel to each other, an insulator 55 insulating the conductors 54 from each other and a shield film 56. The conductor 54 is made of copper alloy, such as brass so as to be conductive. The insulator 55 is made of for example polyethyleneterephthalate: PET) so as to have insulation properties. The insulator 55 covers each conductor 54.
The shield film 56 is made of aluminum alloy, and covers the insulator 55, that is the flat cable 52, as shown in FIGS. 10-12. The shield film 56 prevents that electric noise from an outside of the conductor 54 comes into the conductor 54. The shield film 56 and the conductor 54 are connected electrically to each other by connection, such as ultrasonic welding. For connecting by ultrasonic vibration, a copper foil 57 with slightly narrower width than that of the conductor 54 is piled on a surface of the shield film 56, in other word, the conductor 54, the insulator 55, the shield film 56 and the copper foil 57 are piled in order, and clamped between tools (not shown) for ultrasonic welding. Pressing it in a direction to approach the tools to each other, at least one of the tools is vibrated ultrasonically. Thereby, frictional heat is generated and the insulator 55 is melted. Thus, removing the insulator 55, the conductor 54 and shield film 56 are connected as shown in FIG. 12.
The terminal 53 is connected electrically to the conductor 54 of the shielded FFC 51 structured as mentioned above, as shown in FIGS. 10, 11A. The terminal 53 includes a wire connecting portion 58 to be joined with the flat cable 52 and an electric contact portion 59 continued to the wire connecting portion 58. The wire connecting portion 58 includes a bottom wall 60a and a clamping blade 61 extending perpendicularly from the bottom wall 60a. 
The clamping blade 61 is pierced through the conductor 54 and the insulator 55 at an end portion 62 of the flat cable 52 exposed from the shield film 56, and is bent for clamping. Thereby, the clamping blade 61, that is terminal 53, is connected electrically with the conductor 54 of the flat cable 52.
The electric contact portion 59 includes a bottom wall 60b continued to the bottom wall 60a of the wire connecting portion 58, and is formed into tube shape. The electric contact portion 59 is connected electrically to a mating terminal (not shown). The terminal 53 is received in a connector housing (not shown) and fitted to the mating terminal (not shown). Thereby, the terminal 53 connects electrically the conductor 54 of the flat cable 52 and the mating terminal (not shown).